AIB told the DIRT inquiry that it expected criticism as part of the investigation process, but said the criticism should be fair.
Mr Dermot Gleeson SC, in a closing submission for the bank, said the slogan least likely to appear on election posters for the next general election would probably be "Fair play for the banks".
However, he said, the inquiry chairman, Mr Jim Mitchell, had rightly said the process was "a litmus test for the capacity of parliamentary inquiries to handle issues such as this".
The "true mettle of the process" would be to give even-handed judgments, sometimes against popular sentiment.
Mr Gleeson called on the committee to treat with caution the evidence of two of the witnesses, AIB's former head of group internal audit, Mr Tony Spollen, and Mr Tony Mac Carthaigh, chief inspector of taxes, formerly with the investigation branch.
He said it was "common case" that there was an arrangement on DIRT between the Revenue and AIB.
"I don't say a legally enforceable deal, because that is a question that involves legal questions. I do assert that there was indeed a legally enforceable deal, but I'm not clear that it's for the committee to so decide."
Mr Gleeson pointed out that there was evidence of antipathy, warranted or not, between Mr Spollen and some of his former colleagues.
"He was the only witness who made a resolute attempt to move outside the terms of reference," he said. Mr Spollen referred to the Dana exploration shares debacle.
Mr Spollen had also given evidence that there was no deal between the bank and the Revenue, "but that was a matter in which he was not involved and in which, I think, he would not claim any particular expertise."
Mr Mac Carthaigh's evidence, he said, invited disbelief on half-a-dozen fronts, most of all that part of the documentary record was composed by way of some "pre-planned deception put together by Ms Fullen and Mr O'Mahony in some bizarre and deceptive plot".
Mr Gleeson called on the committee to "expressly reject, whatever else you do", Mr Mac Carthaigh's contention that the records were in some way deceitfully put together.
He was not contending that all their evidence should be accepted, but the committee should dismiss that contention out of the "respect which the committee will owe to them as citizens".
He also called on the Revenue to abandon that contention.
The bank included a written submission of 65 pages, much of which dealt with legal argument, as well as a document of similar length with memos, letters and papers corroborating the bank's position on DIRT liability and its arrangement with the Revenue.
Mr Gleeson, in his oral submission, dealt with some of that legal debate, including the arguments about the legislation or lack of it on what constituted residency in the State.
